1. Field of the Invention
This invention relates to wear liners for railroad cars, and more particularly concerns wear liners between car body center plates and truck bowls, and to wear liners which may be used with or without lubricants between the car body center plate and the truck bowl.
2. Description of the Prior Art
Conventional car body center plates and truck bowl combinations have used a polymer plastic liner between the center plate and the truck bowl. The polymer plastic liners have run into trouble in railroad freight classification hump yards where the freight cars are pushed off a hump to bump into the rear car of a freight train that is being made up. With the freight cars banging into each other like this, the synthetic resin plastic of the liner starts to extrude up between the car body center plate and the truck bowl.
A number of railroads currently grease the inside of truck bowls to provide a low coefficient of friction surface between the car body center plate and the truck bowl in order to permit freight cars to negotiate curves. But it is now being realized that grease does not stay in truck bowls very long because the load bearing pressures are very high, and the grease is being forced out of the truck bowl in a short period of time.
Other conventional wear liners comprise a flat metal plate which is seated on the floor of the truck bowl to provide a low coefficient of friction surface between the bottom of the truck bowl and the wear plate, and to provide a low coefficient of friction surface between the car body center plate and the flat wear liner. Such a wear liner may be held in place by a metal ring which is welded into a groove at about the juncture between the bottom wall of the truck bowl and the side wall of the truck bowl.